Adapting a computer for blind users
Screen reading software
Screen reading software allows a blind person to use a computer by providing spoken descriptions and full keyboard control. The computer can be controlled with keyboard shortcuts instead of a mouse. Screen readers can allow access to: computer menus, web pages, office software and email. Some blind people also use a screen reader with a braille display.
Screen readers can provide spoken description of:
the full screen
a user defined area of the screen
a line, word or individual letters
capital letters, punctuation and symbols
computer system messages
Text-to-speech programs
A screen reader differs from a text-to-speech program in its flexibility and price. While text-to-speech programs are cheaper, they are restricted in what they allow to be read back from the screen and may not provide complete access to a PC for a blind user. This is because they were not originally designed for people with sight problems, but for users with dyslexia or learning difficulties. Because of this navigation around the computer using speech only without any useful vision may not be possible. Different text-to-speech programs will also vary between each other in what features they can offer.
Braille displays
An electronic braille display is a tactile device that is placed under a conventional computer keyboard, which enables the user to read the contents of the computer screen, by touch in braille. They are also known as paperless, soft or refreshable braille displays and vary in size from 20 to 80 braille cells.
Each cell has 6 or 8 pins made of metal or nylon, which are electronically controlled to move up and down, to display a braille version of characters that appear on the computer screen. Braille displays are driven by a screen reader, as described earlier in this information sheet.
Each braille cell shows one character from the screen at a time, which gives the users access to approximately one line of the screen on an 80 cell braille display using grade 1 braille. The displays are designed with buttons and/or bars to enable the user to roam around the screen, reading whichever part they wish. On many displays these buttons can be customised to suit the users needs. These features reduce the need to move the hands from the display to the keyboard.
All displays now have at least one row of touch cursors, these are tiny buttons, one for each braille cell. Their function is crucial - if you move away from the PC cursor to read the rest of the screen with your braille display these tiny buttons allow you to bring the PC cursor to the area of the screen that you are reading with your braille display e.g. to edit that character or word.
Braille can provide layout information more efficiently and using a braille display is described by users as being more accurate. A spelling mistake, for example, is more obvious on a braille display than hearing mispronunciation amongst a lot of speech. It is sometimes said that speech is for speed and braille is for accuracy. For many people braille is their natural way of working and is an essential medium for deafblind people.
- Date: July 2009